Self-contained disposable micro-abrasive blasting tip for dental applications

ABSTRACT

The present invention is a micro-abrasive blasting device ( 75 ) constructed from a disposable pipette structure ( 80 ) comprising a delivery conduit ( 30 ) extending from a delivery conduit inlet ( 35 ) through a tapered section ( 33 ) to form a delivery conduit outlet ( 37 ) and a inlet port ( 27 ); contiguous pipette structure ( 80 ) expands from inlet port ( 27 ) to form a hollow bulb mixing chamber ( 23 ) and then narrows to form a discharge port ( 29 ) section; a discharge conduit ( 10 ) is in fluid communications with discharge port ( 29 ) and extends from a discharge conduit inlet ( 12 ) internal to mixing chamber ( 23 ) to a discharge conduit outlet ( 14 ) external to mixing chamber ( 23 ); a particulate matter ( 50 ) is disposed within mixing chamber wall ( 25 ); discharge conduit inlet ( 12 ) abuts inlet port ( 27 ) preventing particulate matter ( 50 ) from exiting mixing chamber  23 . A separation gap ( 45 ) between the delivery conduit outlet ( 37 ) and discharge conduit inlet ( 12 ) is created as discharge conduit ( 10 ) is displaced so discharge conduit inlet ( 12 ) no longer abuts inlet port ( 27 ); As pressurized-gas is supplied to micro-abrasive blasting device ( 75 ) through the delivery conduit inlet ( 35 ), the pressurized-gas flows through the delivery conduit ( 30 ) and out of the inlet port ( 27 ), into mixing chamber ( 23 ). As flow is initiated, particulate matter ( 50 ) instantaneously mixes with the gas-steam within hollow resilient bulb mixing chamber ( 23 ) and the powder-gas mixture flows through discharge conduit ( 10 ) to strike target surface ( 40 ).

FIELD OF THE INVENTION

The present invention relates generally to the field of devices for propelling abrasive powder with intent to etch the surface of a target material. More specifically, the present invention relates to a micro-abrasive blasting device powered by a pressurized-gas source for use with dental procedures.

Abrasive blasting devices operate on the physical property that gas at a higher pressure flows towards and into gas at lower pressure. When abrasive powder is mixed with gas at higher pressure, the gas carries the abrasive powder as the gas accelerates and flows to the lower pressure. As the gas and abrasive powder blast the target material at high speed, the impact of the particles removes layers of the target material.

In dentistry this technology is known as micro-abrasion and is used to achieve a variety of goals—such as to remove foreign material or to dull a shiny surface, roughen or etch the surface to enhance bonding quality and to remove decay by drilling and cutting tooth structure.

DESCRIPTION OF THE PRIOR ART

A search of the prior art did not disclose any patents that possess the novelty of the instant invention; however the following U.S. patents are considered related:

U.S. Pat. No. Inventor Issue Date 5,197,876 Coston Mar. 30, 1993 5,356,292 Ho Oct. 18, 1994 6,024,566 Burns et al. Feb. 15, 2000 6,951,505 Hertz Oct. 4, 2005 5,839,946 Hertz Nov. 24, 1998 6,287,180 Hertz Sep. 11, 2001 6,004,191 Schur et al. Dec. 21, 1999 6,293,856 Hertz et al. Sep. 25, 2001 Appl. No. Hertz et al. Notice of Allowance 09/939,865 Mailed Apr. 28, 2006 6,354,924 Trafton et al. Mar. 12, 2002 6,083,001 Deardon et al. Jul. 4, 2000 6,093,021 Rainey Jul. 25, 2000 4,475,370 Stark et al. Oct. 9, 1984 6,343,717 Zhang et al. Feb. 5, 2002 6,439,966 Burns et al. Aug. 27, 2002 2,725,684 Crowe Dec. 6, 1955 2,612,732 Ziegler Oct. 7, 1952 4,391,590 Dougherty Jul. 5, 1983 5,199,229 Herold Apr. 6, 1993 3,626,841 Schachter Dec. 14, 1971 2,441,441 Paasche Sept. 5, 1948 6,398,628 Groman Jun. 4, 2002 6,347,984 Groman Feb. 19, 2002 Appl. No. Groman Filed May 13, 2002 10/144,228 Pending Application

Air abrasion devices date back decades with patented inventions by pioneers such as Ziegler U.S. Pat. No. 2,612,732, Crow U.S. Pat. No. 2,725,684, Schachter U.S. Pat. No. 3,626,841 and Paache U.S. Pat. No. 2,441,441.

Over the years two main approaches to air abrasion devices developed with Ziegler and Schechter following one approach and Crowe and Passche following another. One approach has been to provide a stationary mixing apparatus for generating the abrasive laden air stream and delivering the abrasive laden air stream through an extended hand-piece for directing the stream onto the target surface. Another approach has been to integrate the mixing apparatus into the hand-held device.

The first approach facilitates more complex mechanisms and many operational options since the size and weight of the device are of no concern. Because the extended hand-piece delivers the abrasive laden air stream independent of the mixing operation, the hand-piece can be held at any orientation during operation. Deardon et al. U.S. Pat. No. 6,083,001 discloses a dental air abrasion system in which the flow of the particles is electronically controlled by pressure differentials. Rainey U.S. Pat. No. 6,093,021 discloses an automated control system which utilizes a gas stream mounted particulate sensor to regulate fluid flow rates into and around the ultrasonically agitated mixing chamber in order to accurately maintain the abrasive concentration in the air stream. Various methods for reducing the overspray of the abrasive have also been developed for these devices. Ho U.S. Pat. No. 5,356,292, Coston U.S. Pat. No. 5,197,876, and Burns et al. U.S. Pat. No. 6,024,566 disclose add-on splatter guard and collector attachments to air abrasion devices.

In the second approach, the size, weight, and ergonomic shape of the device are significant factors. Herald et al. U.S. Pat. No. 5,199,299 and Burns et al. U.S. Pat. No. 6,439,966 disclose innovative hand-holdable air abrasion devices which mount the mixing apparatus into the hand-piece. The drawback of this approach is that the operation of these devices is limited by the orientation of the mixing chamber.

An adjunct to the second approach has been the concept of simple self-contained air abrasion devices—such as Hertz U.S. Pat. No. 5,839,946 (and its derivative patents U.S. Pat. Nos. 6,287,180, 6,951,505, and Granted application Ser. No. 09/939,865), Groman U.S. Pat. No. 6,398,628 (and its derivative patents U.S. Pat. No. 6,347,984 and Pending application Ser. No. 10/144/228), Schur et al. U.S. Pat. No. 6,004,191, and Trafton et al. U.S. Pat. No. 6,354,924. These devices rely on the air stream to perturb the abrasive and generate the mixing action based on Stark et al. U.S. Pat. No. 4,475,370 fixed air abrasion device for treating dental castings.

Merging of Stark's blow-through mixing method into the hand-piece so the mixing chamber is held between the user's fingers has taken air abrasion art to a new level. Because of their simplified structures, simple self-contained air abrasion devices tend to be less expensive to manufacture and can therefore be marketed to the user as disposable instruments.

With increased emphasis in Medical, Pharmaceutical, Cosmetic and Dental applications on reduced cross-patient contamination, there has been a significant drive towards single usage disposable packaging and devices. With advances in materials and fabrication technologies the cost of these devices has been significantly reduced. Dougherty U.S. Pat. No. 4,391,590 discloses a syringe and stopper like cartridge device for dispensing material while Hertz U.S. Pat. No. 5,839,946 patent discloses the formulation an air abrasion instrument from a syringe and stopper type structure. Both innovations capitalize on the lower cost of fabrication and the well established production methods of a syringe and stopper configuration.

Simple self-contained prior art air abrasion devices support an elongated cylindrical chamber with an inlet conduit for delivering the air into the mixing chamber and a discharge conduit for carrying the air-abrasive mixture out of the mixing chamber. The mixing chambers are utilized as a reservoir for storing the abrasive powder. Once the reservoir is depleted of abrasive material, the devices are discarded and therefore function as disposable instruments which do not require sterilization post intra-oral use.

To prevent the abrasive material from escaping the mixing chamber or becoming contaminated prior to use, simple self-contained prior art air abrasion devices add additional components which seal the inlet and outlet ports and conduits. While the Hertz U.S. Pat. No. 5,839,946, and Schur et al. U.S. Pat. No. 6,004,191 devices include passive caps which must be removed prior to using the instrument, Hetrz U.S. Pat. Nos. 6,951,505 and 6,287,180, and Groman U.S. Pat. Nos. 6,398,628 and 6,347,984 add functional components which actively prevent the abrasive from exiting the mixing chamber. Groman U.S. Pat. No. 6,398,628 has a filter that prevents the abrasive from exiting the device's inlet port and a movable discharge conduit which prevents abrasive material from exiting the mixing chamber when the discharge conduit inlet port abuts the side wall of the mixing chamber. Groman pending application Ser. No. 10/144,228 support a deformable gasket at the discharge port internal to the mixing chamber which opens when flow is present. Hertz U.S. Pat. No. 6,951,505 has a deformable seal at the inlet port external to the mixing chamber which functions as a check-valve that allows the pressurized-gas to enter the instrument but prevents abrasive from exiting the instrument. Groman U.S. Pat. No. 6,398,628 discloses a deformable and movable cap configurations which block both the delivery conduit inlet and discharge conduit outlet prior to use.

Another disposable delivery method disclosed by Zhang et al. U.S. Pat. No. 6,343,717 attempts to address the containment of stored material utilizing a pipette structure. A typical pipette consists of a slender pipe or tube that is used to transfer or measure small quantities of material from one location to another. The most common type of pipette consists of a small tube that widens into a bulb at the middle.

Zhang et al. pipette structure is made of a rigid or resilient material that is pre-filled with a pharmaceutical or cosmetic product and is used once and then discarded. Zhang et al. discloses a plurality of ways by which the disposable pipette can be sealed to contain the material and then unsealed by the user prior to use for dispensing the stored material. According to Zhang's et al. invention the majority of material is retained within the bulb section of the pipette, but Zhang's et al. sealing methods permit the contained material to migrate into the top and bottom tube sections. Although Zhang's et al. use of a pipette structure leads to a very cost effective means of delivering the contained material, Zhang's et al. sealing methods are not compatible with the needs of air abrasion devices.

Pressurized air stream is delivered to the simple self-contained air abrasion devices of Hertz, Groman, Schur, and Trafton via custom connectors which engage the device externally and to form a seal with the device body to deliver the pressurized air to the mixing chamber delivery port. The connectors are designed to supply clean dry air in order to maintain the abrasive powder dry, since any moisture causes clumping of the abrasive material and therefore the malfunction of the device. The dry air is required because the gas delivery conduit leads directly into the mixing chamber; therefore any liquid present at the entry to the device gets trapped in the mixing chamber. Hertz et al. U.S. Pat. No. 6,293,856 discloses a connector with additional conduits for carrying other types of fluids passively through the mixing chamber. This configuration requires a very complex connector to assure the separation of the fluids delivered to the air abrasion instrument without contaminating the mixing chamber. Custom connectors which supply dry air add to the installation cost and complexity of these disposable devices. And because they attach to the body of the devices, these connectors are typically very bulky.

Referring to FIG. 1, prior art self-contained air abrasion devices use a blow-through methodology to agitate the abrasive powder. More specifically, these devices utilize the delivery conduit to deliver the gas stream into the abrasive material. As the gas stream blows through the abrasive material, the abrasive material is agitated. Gravity is utilized to assure that the non-aerated abrasive remains at the bottom of the mixing chamber. As the air stream reverses direction towards the discharge conduit inlet, aerated particles are captured by the air stream. The abrasive laden air stream is pushed out of the mixing chamber through the discharge conduit by the higher pressure gas source.

In their reduction to practice, both the Schur and Groman devices require the user to maintain the orientation of the device so the mixing chamber points downward. The attached user instructions for the Schur and Groman devices outline the specific user instructions cautioning the user about mis-orienting the mixing chamber. To compensate for his shortcoming, the marketed Groman instrument provides a finger bendable discharge conduit. The marketed Schur device provides a bending tool, so the user is able to form the delivery conduit to reach upper surfaces while maintaining the proper orientation of the mixing chamber.

Referring to FIG. 2, if the user attempts to utilize these prior art devices with the mixing chamber horizontal or upside down, the abrasive material is pushed directly into the discharge conduit without being properly mixed with the air steam. This leads to a concentration of abrasive material to exit the device in an uncontrolled manner, which creates a cloud of abrasive dust or clogs up the discharge conduit as the abrasive powder binds. Additionally, in certain orientations the delivery conduit is not immersed in the abrasive material which also disrupts the mixing operation of these prior art devices. In fact, the pressurized-gas exiting the delivery conduit creates a back pressure on the abrasive within the mixing chamber causing the abrasive powder particles to bind together instead of mix with the air stream. Most importantly, these disruption in flow can lead to a defective clinical procedure which either under or over etches the target tooth surface.

The invention disclosed herein solves the following shortcomings with the prior art simple self-contained air abrasion devices:

-   -   1) Eliminates the need for the inlet and outlet caps or other         sealing methods.     -   2) Makes the device insensitive to liquids at the         pressurized-gas connection.     -   3) Makes the air abrasive mixing operation independent of the         orientation of the mixing chamber.     -   4) Eliminates back pressure buildup within the mixing chamber.     -   5) Eliminates the need for a bulky custom connection to the         instrument for pressurized-gas delivery.

In addition, this invention teaches a new innovative method for constructing the air abrasion device out of a continuous tubing formed into a disposable pipette structure.

SUMMARY OF THE INVENTION

Accordingly, several objects and advantages of the present invention are to:

-   1) Reduce component count by utilizing the discharge conduit in     conjunction with the delivery conduit inlet to seal the abrasive     material within the mixing chamber. -   2) Create a bypass to the mixing chamber so liquids in the     pressurized-gas connection are purged out of the system without     contaminating the abrasive within the mixing chamber. -   3) Provide a spherical mixing chamber which assures a distal     separation between the discharge conduit inlet and the abrasive     powder at all mixing chamber orientations. -   4) Eliminate the air stream reversal within the mixing chamber so     back pressure is never created on the abrasive powder. -   5) Extend the delivery conduit external to the mixing chamber so a     slander handheld gas supply connector and standard tube fittings can     be utilized for pressurized-gas delivery. -   6) Make the disposable pipette structure usable for air abrasion     applications in order to further reduce the manufacturing costs.

Still another object of the invention is that the material in the bulb of the pre-filled pipette is protected from contamination or spillage by the discharge conduit.

BRIEF DESCRIPTION OF THE DRAWINGS

Various other objects, advantages, and features of the invention will become apparent to those skilled in the art from the following discussion taken in conjunction with the following drawings, where closely related figures have the same number but different alphabetic suffixes:

FIGS. 1 and 2 are views of prior art micro-abrasive blasting devices.

FIG. 3 are cross-sectional views of the innovative micro-abrasive blasting device and isometric view of the innovative device mounted into a handpiece connector.

FIG. 4 are cross-sectional views of the innovative micro-abrasive blasting device fabricated out of a pipette structure.

FIGS. 5 and 6 are isometric and cross-sectional views of micro-abrasive blasting devices with spherical mixing chamber.

FIG. 7 are cross-sectional views of the preferred micro-abrasive blasting device with discharge conduit bearing integral to the pipette structure.

FIGS. 8 and 9 are cross-sectional views of the preferred micro-abrasive blasting device with an integrated protective nozzle guard and integrated particle deflector integral to the pipette structure.

REFERENCE NUMERALS IN DRAWINGS

10 discharge conduit 12 discharge conduit inlet 14 discharge conduit outlet 23 mixing chamber 25 mixing chamber wall 27 inlet port 29 discharge port 30 delivery conduit 32 delivery conduit external section 33 delivery conduit tapered section 34 delivery conduit internal section 35 delivery conduit inlet 37 delivery conduit outlet 40 target surface 45 separation gap 48 pressure gradient 50 particulate matter 55 handheld supply connector 75 micro-abrasive blasting device 80 pipette structure 82 discharge conduit bearing 83 Discharge conduit stop 85 protective nozzle guard 87 nozzle guard separation point 90 particle deflector 93 particle deflector separation point 95 capped position end 97 mixing position end

DETAILED DESCRIPTION OF THE INVENTION INCLUDING PREFERRED EMBODIMENTS

As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriately detailed structure.

Reference is now made to the drawings, wherein like characteristics and features of the present invention shown in the various figures are designated by the same reference numerals.

First Preferred Embodiment

Referring to FIG. 3, a micro-abrasive blasting device 75 is disclosed; Micro-abrasive blasting device 75 comprises a mixing chamber 23 formed by a mixing chamber wall 25 and supports a inlet port 27 and a discharge port 29; a delivery conduit 30 extending from a delivery conduit inlet 35 external to mixing chamber 23 to a delivery conduit outlet 37 internal to mixing chamber 23, by means of protruding into mixing chamber 23 through mixing chamber wall 25 at inlet port 27; a discharge conduit 10 is in fluid communications with mixing chamber 23 at discharge port 29, and extending from a discharge conduit inlet 12 internal to mixing chamber 23 to a discharge conduit outlet 14 external to mixing chamber 23; a particulate matter 50 is disposed within mixing chamber 23.

Delivery conduit 30 comprises a delivery conduit external section 32 external to mixing chamber 23 and a delivery conduit internal section 34 internal to mixing chamber 23 and a connecting delivery conduit tapered section 33; external section 32 of delivery conduit 30 is preferably straight and preferably supports an outer and inner diameter that fits into standard tube and hose connectors such as push-in or push-on connector types; internal section 34 of delivery conduit 30 preferably supports an inner diameter that is equivalent to the outer diameter of discharge conduit inlet 12.

Referring to FIG. 3D, extending delivery conduit 30 external to the mixing chamber 23 facilitates a connection to a handheld pressurized-gas supply connector 55. Not only does this innovative configuration simplify the type of connection required for supplying the pressurized-gas and therefore the cost of the air supply adaptor, it also facilitates a more narrow connection to the air abrasion device. Whereas, prior art devices connect to the mixing chamber body, this preferred embodiment connects to a narrower delivery conduit. Therefore, the innovative micro-abrasive blasting device 75 may be mounted as a disposable tip onto a non-disposable handheld supply connector 55. While handheld supply connector 55 is held by the user's fingertips, delivery conduit 30 of micro-abrasive blasting device 75 mounts into handheld supply connector 55 downstream of the user's fingertips. Because the innovative micro-abrasive blasting device 75 does not support the user's grip and bulky supply connector, micro-abrasive blasting device 75 can be made shorter and of less rigid material. This configuration greatly decreases the complexity and cost of the micro-abrasive blasting device 75.

Referring to FIG. 3A, discharge conduit inlet 12 abuts delivery conduit outlet 37 as to prevent particulate matter 50 from exiting mixing chamber 23, thereby sealing particulate matter 50 within mixing chamber 23. As delivery conduit external section 32 engages with a pressurized-gas source, pressurized-gas is delivered to delivery conduit 30 at delivery conduit inlet 35; the pressurized-gas passes through delivery conduit 30 into discharge conduit 10 to exit micro-abrasive blasting device 75 at discharge conduit outlet 14. Since discharge conduit inlet 12 abuts delivery conduit outlet 37 the pressurized gas can not enter mixing chamber 23. Therefore, any moisture or liquid residue contained in or carried by the pressurized-gas does not enter mixing chamber 23 and is discharged through micro-abrasive blasting device 75.

Referring to FIG. 3B, a separation gap 45 between the delivery conduit outlet 37 and discharge conduit inlet 12 is created as discharge conduit 10 is displaced so discharge conduit inlet 12 no longer abuts delivery conduit outlet 37; As pressurized-gas is supplied to micro-abrasive blasting device 75 through delivery conduit inlet 35, the pressurized-gas flows through delivery conduit 30 and out of delivery conduit outlet 37 into mixing chamber 23. When gas flow is present, particulate matter 50 instantaneously mixes with the flowing gas and is dispensed through discharge conduit 10 to strike target surface 40. Once mixing chamber 23 is depleted of particulate matter 50, micro-abrasive blasting device 75 is removed from the pressurized-gas source and discarded.

Second Preferred Embodiment

Referring to FIG. 4, a micro-abrasive blasting device 75 is comprised of a hollow resilient round tubular pipette structure 80 constructed of a thermoplastic material such as polycarbonate, polyethylene, polyester, polystyrene, polypropylene, polysulfone, polyurethane, ethylene-vinyl-acetate or the like. The material may be transparent, translucent, opaque, or pigmented to indicate the type of abrasive powder contained within the sealed mixing chamber. Pipette structure 80 preferably has a circular cross section but can also be fabricated out of other cross sectional shapes.

Micro-abrasive blasting device 75 is comprised of a pipette structure 80 which consists of three sections, a hollow bulb section forming a mixing chamber 23; a open ended hollow tubular delivery conduit 30 section smaller in diameter and contiguous with the bulb section at inlet port 27, for delivery of pressurized-gas; a hollow tubular discharge port 29 section smaller in diameter and contiguous with the bulb section, for discharging abrasive laden gas stream; a discharge conduit 10 in fluid communications with discharge port 29, and extending from a discharge conduit inlet 12 internal to mixing chamber 23 to a discharge conduit outlet 14 external to mixing chamber 23; a particulate matter 50 is disposed within mixing chamber 23. Preferably, delivery conduit 30 section extends from a delivery conduit inlet 35 through a external section 32 and a tapered section 33 to form a delivery conduit outlet 37 and a inlet port 27.

The outer and/or inner diameter of delivery conduit external section 32 is preferably selected to fit standard tube or hose fittings, while the inner diameters of inlet port 27 and discharge port 29 preferably support an inner diameter that is equivalent to or less than the outer diameter of discharge conduit 10. Design selections of these diameters may eliminate or reverse the gradient of delivery conduit tapered section 33, rendering delivery conduit 30 a straight tube. The diameter of hollow resilient bulb mixing chamber 23 is preferably selected to support the appropriate quantity of particulate matter 50 to at least perform one dental procedure.

Pipette structure 80 may be formed via blow-molding and/or tube swaging techniques, or other thermo-forming processes. These methods would typically require that one of the ends of the tubular pipette structure 80 be sealed in order to entrap pressurized-gas for forming the component during the blow-molding process. The sealed end may be formed at the delivery conduit inlet 35 of delivery conduit 30 section or at the tip of discharge port 29 section. The sealed end may be trimmed off during the assembly process of micro-abrasive blasting device 75 or just punctured or cut to permit air flow into micro-abrasive blasting device 75 when mounted onto a pressurized-gas connector. Additionally, the pressurized-gas connector could support cutting or puncturing means for breaking the blow-molded seal when delivery conduit 30 is mounted on the pressurized-gas connector.

Referring to FIG. 4A, discharge conduit inlet 12 fits within or abuts inlet port 27 preventing particulate matter 50 from exiting mixing chamber 23. As delivery conduit external section 32 engages with a pressurized-gas source, pressurized-gas is delivered to delivery conduit 30 at delivery conduit inlet 35; the pressurized-gas passes through delivery conduit 30 into discharge conduit 10 to exit micro-abrasive blasting device 75 at discharge conduit outlet 14. Since discharge conduit inlet 12 abuts inlet port 27 the pressurized gas can not enter mixing chamber 23.

Referring to FIG. 4B, a separation gap 45 between the inlet port 27 and discharge conduit inlet 12 is created as discharge conduit 10 is displaced so discharge conduit inlet 12 no longer abuts inlet port 27; As pressurized-gas is supplied to micro-abrasive blasting device 75 through delivery conduit inlet 35, the pressurized-gas flows through delivery conduit 30 and out of inlet port 27, into mixing chamber 23. As flow is initiated, particulate matter 50 instantaneously mixes with the gas-steam within hollow resilient bulb mixing chamber 23 and the powder-gas mixture flows through discharge conduit 10 to strike target surface 40.

Third Preferred Embodiment

Referring to FIG. 5, this preferred micro-abrasive blasting device 75 is also constructed of a contiguous pipette structure 80 and operates as the preferred embodiments of FIGS. 3 and 4. However, pipette structure 80 of the FIG. 5 embodiment supports a mixing chamber wall 25 constructed to form a hollow spherical bulb mixing chamber 23. The spherical shape of mixing chamber 23 assures a distal separation between the discharge conduit inlet 12 and the particulate matter 50 at all orientations of mixing chamber 23.

Referring to FIG. 6A, when micro-abrasive blasting device 75 is operated in a horizontal orientation, particulate matter 50 is pulled by gravity to the mixing chamber wall 25 at the bottom surface of mixing chamber 23. Therefore, during operation, the spherical configuration of mixing chamber 23 keeps particulate matter 50 distant from discharge conduit inlet 12, thereby maintaining the proper mixing action.

Referring to FIG. 6B, when micro-abrasive blasting device 75 is operated in a vertical orientation, the spherical shape of mixing chamber 23 also assures a distal separation between the discharge conduit inlet 12 and the particulate matter 50 at all mixing chamber 23 orientations. Additionally, the elimination of the delivery conduit internal section—referred to in the embodiment of FIG. 3 as delivery conduit internal section 34—assures that the pressurized gas stream entering mixing chamber 23 at inlet port 27 always directs the pressurized-gas into particulate matter 50 thereby eliminating the potential for back pressure on particulate matter 50.

Referring to FIG. 5, a discharge conduit stop 83 is attached to discharge conduit 10 so discharge conduit stop 83 moves with discharge conduit 10 within mixing chamber 23 from inlet port 27 to discharge port 29. Discharge conduit stop 83 provides a mechanical restriction to the displacement of discharge conduit 10 by creating a restriction at inlet port 27 and discharge port 29. When discharge conduit stop 83 abuts inlet port 27, discharge conduit inlet 12 is properly positioned to seal mixing chamber 23. When discharge conduit stop 83 abuts discharge port 29, discharge conduit inlet 12 is properly positioned to form separation gap 45. Discharge conduit stop 83 could be integral to discharge conduit 10 through a flaring or bulging of discharge conduit 10, a component mounted onto discharge conduit 10 via a gluing, swaging, heat-shrinking, or welding process etc., or simply a drop of dispensed glue.

Referring to FIG. 5A, as discharge conduit inlet 12 abuts inlet port 27, discharge conduit stop 83 is positioned at inlet port 27, restricting discharge conduit inlet 12 from protruding too deep through inlet port 27. Preferably, discharge conduit stop 83 locates discharge conduit inlet 12 within inlet port 27 such that potential liquid residue smoothly passes through micro-abrasive blasting device 75.

Referring to FIG. 5B, discharge conduit 10 is displaced so discharge conduit inlet 12 no longer abuts inlet port 27. The displacement of discharge conduit 10 is restricted by the movement of discharge conduit stop 83 to discharge port 29. Preferably, discharge conduit stop 83 locates discharge conduit inlet 12 at the geometrical center of spherical mixing chamber 23.

Referring to FIG. 5C, the extension of delivery conduit 30 external to the mixing chamber 23 facilitates a more narrow connection to the air abrasion device via a handheld pressurized-gas supply connector 55. Whereas, prior art devices connect to the mixing chamber body, this preferred embodiment connects to a narrower delivery conduit 30. Therefore, the innovative micro-abrasive blasting device 75 may be mounted as a disposable tip onto a non-disposable handheld supply connector 55. While handheld supply connector 55 is held by the user's fingertips, delivery conduit 30 of micro-abrasive blasting device 75 mounts into handheld supply connector 55 downstream of the user's fingertips. Because the innovative micro-abrasive blasting device 75 does not support the user's grip and bulky supply connector, micro-abrasive blasting device 75 can be made shorter and of less rigid material. This configuration greatly decreases the complexity and cost of the micro-abrasive blasting device 75.

Further Enhancements to Preferred Embodiments

Referring to FIG. 7, contiguous pipette structure 80 is extended to include an additional hollow bulb section to form a discharge conduit bearing 82. The discharge conduit bearing 82 is a tubular extension of the discharge port 29 section, elongated from a capped position end 95 to a mixing position end 97 with a diameter equal to or greater than discharge conduit 10. Discharge conduit bearing 82 provides mechanical support to discharge conduit 10, to assure discharge conduit 10 properly displaces away from inlet port 27; a discharge conduit stop 83 is attached to discharge conduit 10 so discharge conduit stop 83 moves with discharge conduit 10 within discharge conduit bearing 82 from the capped position end 95 to the mixing position end 97. Discharge conduit stop 83 in conjunction with discharge conduit bearing 82 provides a mechanical restriction to the displacement of discharge conduit 10. When discharge conduit stop 83 abuts capped position end 95, discharge conduit inlet 12 is properly positioned to seal mixing chamber 23. When discharge conduit stop 83 abuts mixing position end 97, discharge conduit inlet 12 is properly positioned to form separation gap 45.

Referring to FIG. 8, contiguous pipette structure 80 is extended to include a protective nozzle guard 85. Protective nozzle guard 85 is constructed by extending pipette structure 80 so it encompasses discharge conduit outlet 14, thereby providing protection to discharge conduit 10 external to mixing chamber 23. Protection of the delivery conduit is important to prevent damage to the delivery conduit during shipping and from the delivery conduit puncturing other surrounding devices in bulk packaging. Nozzle guard 85 also prevents the delivery conduit from sticking the user when mounting micro-abrasive blasting device 75 onto the pressurized-gas connector.

Preferably, protective nozzle guard 85 is removed prior to use, by pulling protective nozzle guard 85 coaxially to discharge conduit 10, thereby fully exposing discharge conduit 10. Preferably, perforation to pipette structure 80 is provided at nozzle guard separation point 87 as to weaken pipette structure 80 at nozzle guard separation point 87. Pulling on protective nozzle guard 85 coaxially to discharge conduit 10, causes pipette structure 80 to separate at nozzle guard separation point 87 allowing the removal of protective nozzle guard 85 to expose discharge conduit 10.

Referring to FIG. 9, contiguous pipette structure 80 is extended to include a portion of a hollow bulb section to form a particle deflector 90. Particle deflector 90 is constructed by extending pipette structure 80 to preferably form a semi-spherical bulb structure. Particle deflector 90 is positioned on discharge conduit 10 as to deflect particulate matter 50 ricocheting off the target surface during use.

Preferably, perforation to pipette structure 80 is provided at particle deflector separation point 93 as to weaken pipette structure 80 at particle deflector separation point 93. Pulling particle deflector 90 coaxially to discharge conduit 10, separates particle deflector 90 at particle deflector separation point 93 to permit the movement of particle deflector 90 along discharge conduit 10. Preferably particle deflector 90 is positioned near discharge conduit outlet 14 as to deflect particulate matter 50 ricocheting off the target surface during use.

Of course, pipette structure 80 may be constructed to include both protective nozzle guard 85 and particle deflector 90.

Mixing Method

Referring to FIG. 3C, a separation gap 45 between the delivery conduit outlet 37 and discharge conduit inlet 12 generates rapidly expanding and contracting gas-stream that forms a pressure gradient 48. The rapid expansion of the gas-stream occurs as the gas-stream exits the narrow delivery conduit outlet 37 and expands into the wider mixing chamber 23. The rapid contraction of the gas-stream occurs as the gas-stream flows from the wider mixing chamber 23 into the narrower discharge conduit inlet 12. Because mixing chamber 23 is a closed-system, the volumetric flow rate into mixing chamber 23 must equal the volumetric flow rate out of mixing chamber 23.

Therefore, the expansion and contraction of the gas-stream across separation gap 45 is accompanied by a localized pressure gradient 48 at separation gap 45. Pressure gradient 48 across separation gap 45 within mixing chamber 23 agitates particulate matter 50 causing particulate matter 50 to aerate. The aerated particulate matter 50 particles are pulled into the gas-stream at separation gap 45, generating an abrasive laden gas stream into discharge conduit inlet 12 and out of discharge conduit outlet 14. Because pressure gradient 48 across separation gap 45 is independent of mixing chamber 23 orientations, agitation also is independent of the orientation of mixing chamber 23.

This mixing method is independent of the mixing chamber shape as long as the mixing chamber 23 is wider than the delivery conduit outlet 37 and discharge conduit inlet 12. In the absence of delivery conduit outlet 37 where delivery conduit 30 terminates at inlet port 27, this innovative mixing method still applies as pressure gradient 48 is formed across separation gap 45.

Since separation gap 45 controls the rapidness by which the gas-stream expands and contracts, the distance of separation gap 45 controls the agitation rate of particulate matter 50 within mixing chamber 23. Therefore, the quantity of particulate matter 50 introduced into the gas-steam is selectable by the position of discharge conduit inlet 12 with respect to delivery conduit outlet 37 or inlet port 27.

From the description above, the following advantages of the present invention become evident:

-   (a) Use of the delivery conduit to seal the mixing chamber, thereby:     -   1. reducing the component count; and     -   2. making disposable pipette structure usable for air abrasion         applications. -   (b) Use the delivery conduit to create a bypass to the mixing     chamber, thereby eliminating liquid entrapment within the mixing     chamber. -   (c) Extending the delivery conduit external to the mixing chamber,     thereby making the device adaptable to a handheld gas supply     connector and standard tube fitting. -   (d) Generation of a localized pressure gradient within the mixing     chamber to generate and control powder agitation rates. -   (e) Use of a spherical mixing chamber to deliver consistent powder     perturbation at all mixing chamber orientations. -   (f) Simplified construction using contiguous pipette structure     fabricated to form the body of the micro-abrasion device.

While the invention has been described, disclosed, illustrated and shown in various terms or certain embodiments or modifications which it has assumed in practice, the scope of the invention is not intended to be, nor should it be deemed to be, limited thereby and such other modifications or embodiments as may be suggested by the teachings herein are particularly reserved especially as they fall within the breadth and scope of the claims here appended.

SUMMARY, RAMIFICATION, AND SCOPE

The present invention accomplishes the above-stated objectives, as well as others, as may be determined by a fair reading and interpretation of the entire specification.

Accordingly, the reader will see that the present invention is a micro-abrasive blasting device with reduced components, simplified construction, enhanced mixing methodology, and mountable to handheld gas supply connector.

Furthermore, the present invention has the additional advantages in that

-   -   it provides a more narrow pressurized-gas supply connection.     -   it provides a sealed device that is resistant to fluid         contamination.     -   it provides a reliable device that delivers a consistent         quantity of abrasive at any orientation.     -   it provides the user with ability to select powder delivery         rates by external manipulation of the discharge conduit         position.     -   It provides a simplified construction methodology which reduces         the manufacturing cost of the product.

Thus the scope of the invention should be determined by the appended claims and their legal equivalents, rather than by the examples given. 

1. A micro-abrasive blasting device, comprising: a chamber having a chamber wall and a hollow interior; an inlet port in said chamber wall; a discharge port in the chamber wall; a tubular delivery conduit section contiguous with said chamber wall elongated from a delivery conduit inlet external to said chamber to a delivery conduit outlet terminating at said inlet port; a tubular discharge section contiguous with said chamber wall elongates from said discharge port external to said chamber; a discharge conduit elongated from a discharge conduit inlet internal to the chamber to a discharge conduit outlet external to the chamber and extending through said tubular discharge section and in fluid communications with said tubular discharge section; a quantity of particulate matter disposed within said chamber; wherein a handheld pressurized-gas supply connector mounts to said tubular delivery conduit section external to the chamber; wherein: said discharge conduit inlet abuts delivery conduit outlet to seal said particulate matter within said chamber.
 2. The apparatus, according to claim 1, wherein: pressurized-gas supplied to said tubular delivery conduit section passes through the delivery conduit outlet into the chamber to generate an abrasive laden gas stream out of said discharge conduit.
 3. The apparatus, according to claim 1, wherein: pressurized-gas supplied to delivery conduit inlet passes through the delivery conduit and discharge conduit without entering the chamber.
 4. The apparatus, according to claim 1, wherein: the displacement of said discharge conduit inlet away from delivery conduit outlet unseals the chamber to allow pressurized-gas flow through the chamber to generate an abrasive laden gas stream.
 5. The apparatus, according to 1, wherein: said chamber is spherical.
 6. A micro-abrasive blasting device, comprising: a chamber having a chamber wall and a hollow interior; an inlet port in said chamber wall; a discharge port in the chamber wall; a tubular delivery conduit section contiguous with said chamber wall elongated from a delivery conduit inlet external to said chamber to a delivery conduit outlet terminating at said inlet port; a tubular discharge section contiguous with said chamber wall elongates from said discharge port external to said chamber; a discharge conduit elongated from a discharge conduit inlet internal to the chamber to a discharge conduit outlet external to the chamber and extending through said tubular discharge section and in fluid communications with said tubular discharge section; a quantity of particulate matter disposed within said chamber; wherein a handheld pressurized-gas supply connector mounts to said tubular delivery conduit section external to the chamber; wherein: a discharge conduit stop mounted to said discharge conduit is disposed within the mixing chamber to prevent the extraction of the discharge conduit out of the tubular delivery conduit section and tubular discharge section.
 7. A pre-filled disposable pipette structure for micro-abrasive blasting device, comprising: a hollow tubular pipette structure; said pipette structure having a hollow bulb section forming a mixing chamber; said pipette structure further having a open ended hollow tubular delivery section smaller in diameter and contiguous with the bulb section, for delivery of pressurized-gas; said pipette structure also having a hollow tubular discharge section smaller in diameter and contiguous with the bulb section, for discharging abrasive laden gas stream; a quantity of particulate matter disposed within said mixing chamber; a discharge conduit elongated from a discharge conduit inlet to a discharge conduit outlet; wherein said discharge conduit is positioned within said tubular discharge section of said pipette structure and in fluid communications with said tubular discharge section of said pipette structure so said discharge conduit inlet is internal to the mixing chamber and discharge conduit outlet is external to the mixing chamber.
 8. The pre-filled disposable pipette structure, according to claim 7, wherein: a pressurized-gas connector mounts to said delivery section.
 9. The apparatus, according to claim 8, wherein: pressurized-gas supplied to delivery section passes through the delivery conduit outlet into the chamber to generate an abrasive laden gas stream out of said discharge conduit.
 10. The pre-filled disposable pipette structure, according to claim 7, wherein: said discharge conduit inlet abuts delivery section to seal said particulate matter within said mixing chamber.
 11. The apparatus, according to claim 10, wherein: pressurized-gas delivered to delivery section passes through the delivery section and discharge conduit without entering the mixing chamber.
 12. The apparatus, according to claim 10, wherein: the displacement of said discharge conduit inlet away from delivery section unseals the mixing chamber to allow pressurized-gas flow through the mixing chamber to generate an abrasive laden gas stream.
 13. The pre-filled disposable pipette structure, according to claim 7, wherein: said pipette structure is constructed of a thermoplastic material selected from a group consisting of: polycarbonate, polyethylene, polyester, polystyrene, polypropylene, polysulfone, polyurethane, or ethylene-vinyl-acetate.
 14. The pre-filled disposable pipette structure, according to claim 7, wherein: the pipette structure is formed by extrusion blow molding in a two-piece mold.
 15. The pre-filled disposable pipette structure, according to claim 7, wherein: the pipette structure is formed by thermoforming a plastic tube.
 16. The pre-filled disposable pipette structure, according to claim 7, wherein: said mixing chamber is spherical.
 17. The pre-filled disposable pipette structure, according to claim 7, wherein: said pipette's hollow structure is configured in cross section as selected from a group consisting of round, oval, square, rectangular and polygonal shapes.
 18. The pre-filled disposable pipette structure, according to claim 7, wherein: said pipette's bulb section has a cylindrical configuration with each end having a cone-shaped taper interfacing on one end with the delivery tube section, and on the other end with the discharge tubular section.
 19. The apparatus, according to claim 1, wherein: said chamber is configured in cross section as selected from a group consisting of round, oval, square, rectangular and polygonal shapes.
 20. The pre-filled disposable pipette structure, according to claim 7, wherein: a discharge conduit stop mounted to said discharge conduit is disposed within the mixing chamber to restrict the movement range of the discharge conduit.
 21. The apparatus, according to claim 1, wherein: said delivery conduit outlet terminates at the inlet port of said chamber.
 22. The apparatus, according to claim 6, wherein: pressurized-gas supplied to said tubular delivery conduit section passes through the delivery conduit outlet into the chamber to generate an abrasive laden gas stream out of said discharge conduit.
 23. The apparatus, according to claim 6, wherein: pressurized-gas supplied to delivery conduit inlet passes through the delivery conduit and discharge conduit without entering the chamber.
 24. The apparatus, according to claim 6, wherein: the displacement of said discharge conduit inlet away from delivery conduit outlet unseals the chamber to allow pressurized-gas flow through the chamber to generate an abrasive laden gas stream.
 25. The apparatus, according to claim 6, wherein: said delivery conduit outlet terminates at the inlet port of said chamber.
 26. The apparatus, according to claim 6, wherein: said chamber is spherical.
 27. The apparatus, according to claim 6, wherein: said chamber is configured in cross section as selected from a group consisting of round, oval, square, rectangular and polygonal shapes. 